How to fix a Power tool Battery that Won't take charge

What happens here

This project provides a step-by-step guide on how to revive a deeply discharged Milwaukee M18 battery that the charger refuses to recognize or charge. The method involves using jumper wires to temporarily connect the 'dead' battery to a fully charged battery of the same type, allowing a small current to flow and wake up the protection circuit in the 'dead' battery. Once jump-started, the battery can then be charged normally using its original charger. The video also briefly touches upon adapters for older DeWalt tools and highlights how certain third-party accessories can prematurely drain batteries, leading to this issue.